I have experience with both the UK and US immigration systems. I agree, it is very easy with how complicated the processes can be to make mistakes, even seemingly big ones, just by misunderstanding a single requirement. Even non-immigration lawyers make serious errors.
> Lucas made his application for naturalisation on 14 May 2014, a couple of weeks before the expiry of his visa.
I'm playing devil's advocate here, but neither indefinite leave to remain OR naturalization would be processed in "a couple of weeks." So even if he had filled the right application he might have ran into problems.
As the article points out, indefinite leave does technically extend their existing visa (whereas citizenship does not), but in both cases you have the same issue: If you're denied then you get deported since your visa has expired.
They should have extended their existing visa first, only then apply for indefinite leave to remain or if eligible citizenship. Otherwise you've built a house of cards, which is one denial away from deportation.
> So instead of Lucas’s application being promptly returned to him [...] It took eight months for him to receive a refusal of his application with the above explanation
That exceeds the government's estimates, but they tell you before you apply it can take 6+ months:
https://www.gov.uk/government/organisations/uk-visas-and-imm...
They don't even look at the application until it is processed, and there's a huge backlog. Plus they cannot deny until the application is fully vetted, otherwise they might miss another avenue for acceptance, or it might be a data problem their side.
Essentially the article is complaining that the other applicants that applied before him were processed before him.
It is unfortunate what happened to him after the initial mistake, and I won't defend that, but his mistake wasn't only applying for the wrong thing, he also left it until the last possible moment.